Engineered retroviral virus-like particles for receptor targeting

Cytochalasin-B-Inducible Nanovesicle Mimics of Natural Extracellular Vesicles That Are Capable of Nucleic Acid Transfer

Extracellular vesicles provide cell-to-cell communication and have great potential for use as therapeutic carriers. This study was aimed at the development of an extracellular vesicle-based system for nucleic acid delivery. Three types of nanovesicles were assayed as oligonucleotide carriers: mesenchymal stem cell-derived extracellular vesicles and mimics prepared either by cell treatment with cytochalasin B or by vesicle generation from plasma membrane. Nanovesicles were loaded with a DNA oligonucleotide by freezing/thawing, sonication, or permeabilization with saponin. Oligonucleotide delivery was assayed using HEK293 cells. Extracellular vesicles and mimics were characterized by a similar oligonucleotide loading level but different efficiency of oligonucleotide delivery. Cytochalasin-B-inducible nanovesicles exhibited the highest level of oligonucleotide accumulation in HEK293 cells and a loading capacity of 0.44 ± 0.05 pmol/µg. The loaded oligonucleotide was mostly protected from nuclease action.

His-tagged norovirus-like particles: A versatile platform for cellular delivery and surface display

In addition to vaccines, noninfectious virus-like particles (VLPs) that mimic the viral capsid show an attractive possibility of presenting immunogenic epitopes or targeting molecules on their surface. Here, functionalization of norovirus-derived VLPs by simple non-covalent conjugation of various molecules is shown. By using the affinity between a surface-exposed polyhistidine-tag and multivalent tris-nitrilotriacetic acid (trisNTA), fluorescent dye molecules and streptavidin-biotin conjugated to trisNTA are displayed on the VLPs to demonstrate the use of these VLPs as easily modifiable nanocarriers as well as a versatile vaccine platform. The VLPs are able to enter and deliver surface-displayed fluorescent dye into HEK293T cells via a surface-attached cell internalization peptide (VSV-G). The ease of manufacturing, the robust structure of these VLPs, and the straightforward conjugation provide a technology, which can be adapted to various applications in biomedicine.

Current approaches in SELEX: An update to aptamer selection technology

Systematic evolution of ligands by exponential enrichment (SELEX) is a well-established and efficient technology for the generation of oligonucleotides with a high target affinity. These SELEX-derived single stranded DNA and RNA molecules, called aptamers, were selected against various targets, such as proteins, cells, microorganisms, chemical compounds etc. They have a great potential in the use as novel antibodies, in cancer theragnostics and in biomedical research. Vast interest in aptamers stimulated continuous development of SELEX, which underwent numerous modifications since its first application in 1990. Novel modifications made the selection process more efficient, cost-effective and significantly less time-consuming. This article brings a comprehensive and up-to-date review of recent advances in SELEX methods and pinpoints advantages, main obstacles and limitations. The post-SELEX strategies and examples of application are also briefly outlined in this review.